evaporation in a freezer?

[bert]

Dear all,


Maybe not the right place to ask, but do you think that it is likely that acetonitrile evaporates in a freezer at -20 degrees Celsius? We stored some calibration samples for over a year and now find an increase in concentration of approximately 20% . Samples were stored in polypropylene screw cap tubes (no inlay in the cap).
Can you share your experiences?

Thanks, Bert

[krickos]

Hi

Well seems like it can happen depending on type of lids and solvent.

Personally I have seen APIs stored in frezzer (~-20°C) lose a few hundred ppms methanol over time (weeks)(snap lid).

Also several collegues has noted that dichloromethane can "wander" from one bottle to another in refridegerators (+2-8°C).

So seen over a full years time I am not completly surprised.

[Peter Apps]

For sure this can happen, even if the solvent is frozen solid, it still has a vapour pressure, and the vapour can still diffuse through the wall or cap of the container, or through any gaps.

Peter